Original Research Paper
Electronics
Ahmad Mouri Zadeh Khaki; Ebrahim Farshidi
Articles in Press, Accepted Manuscript, Available Online from 30 April 2020
Abstract
In this paper, a novel continuous-time 1-1 MASH ∆∑ Time-to-digital converter (TDC) is presented. Since the proposed design utilizes 12-bit quantizer based on Gated Switched-Ring Oscillator (GSRO) for both stages, it has been implemented all-digitally. By using a novel structure, only one multi-bit ...
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In this paper, a novel continuous-time 1-1 MASH ∆∑ Time-to-digital converter (TDC) is presented. Since the proposed design utilizes 12-bit quantizer based on Gated Switched-Ring Oscillator (GSRO) for both stages, it has been implemented all-digitally. By using a novel structure, only one multi-bit counter is employed for both stages, therefore the required hardware for implementation of this work is much less than conventional TDCs. As a result, complexity, chip area and power consumption would decrease considerably. We implemented the proposed design prototype on an Altera Stratix IV FPGA board. Measured results demonstrate that although this work uses less complex architecture in comparison with previous works, it provides appropriate performance such as 60.7 dB SNR within 8 MHz signal bandwidth at 400 MHz sampling rate while consuming 2.79 mW that reveals suitability of the proposed TDC to be incorporated in fast and accurate applications such as ADPLLs and high-resolution photoacoustic tomography.
Original Research Paper
Hardware
Hamed Khanmirza; Arash Oloomi
Articles in Press, Accepted Manuscript, Available Online from 11 May 2020
Abstract
Nowadays, video hosting services receive and stream videos using standard protocols like Real-Time Messaging Protocol (RTMP). During the streaming process, video file streams are usually divided into small multi-second parts, and the player receives these parts instead of the whole file at once. Most ...
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Nowadays, video hosting services receive and stream videos using standard protocols like Real-Time Messaging Protocol (RTMP). During the streaming process, video file streams are usually divided into small multi-second parts, and the player receives these parts instead of the whole file at once. Most of the streaming protocols are capable of adaptive streaming and tolerating faults like device failures, and link disconnections. Faults might affect the performance of live streaming in terms of packet loss, latency, jitter, and video quality. The software-defined networking (SDN) paradigm has also gained momentum in enterprise networks due to its lower-cost management and better network utilization. However, full migration from the current networks to the SDN model is not practical. The purpose of this study is to investigate the effectiveness of fault tolerance mechanisms of RTMP protocol on hybrid SDNs. In this paper, a practical and straightforward hybrid network architecture is proposed for gradual migration from traditional IP networks. Then, the performance of the RTMP protocol is tested for live video streaming on this network in the face of various faults. The results obtained from different experiments with different streams facing multiple failures show that the proposed network performs better in restoring RTMP streams compared to traditional networks.
Original Research Paper
Communications
Mohsen Sheikh-Hosseini
Articles in Press, Accepted Manuscript, Available Online from 11 May 2020
Abstract
This paper investigates multiuser detection for space-time block coded (STBC) transmission over a flat-fading multiple-input multiple-output multiple-access channel consisting of J co-channel users each with N antennas and a zero-forcing coherent receiver equipping with M receiving antennas. For the ...
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This paper investigates multiuser detection for space-time block coded (STBC) transmission over a flat-fading multiple-input multiple-output multiple-access channel consisting of J co-channel users each with N antennas and a zero-forcing coherent receiver equipping with M receiving antennas. For the cases in which M=J , it was previously claimed that it is impossible to extend this receiver to general scenarios of orthogonal STBC transmission with J>2 and N>2 . This paper provides a theorem allowing this extension to any scenarios satisfying the theorem condition. Describing in more details, we first prove that zero-forcing receiver of M=J antennas can successfully extend to any STBC transmission over MIMO multiple-access systems which provides an Alamouti-like structure for the inner product of equivalent channels between different receive antennas and users. Then, in order to gain more insight, the theorem role on extending zero-forcing receiver to transmission of orthogonal STBC over MIMO multiple-access systems with J>2 and N>2 , and also to other STBC schemes like generalized coordinate interleaved orthogonal design and Quasi-orthogonal STBC is investigated in more details. Finally, the average symbol error rate of considered scenarios are numerically evaluated and compered for different STBC schemes with various numbers of J and N.
Original Research Paper
Image Processing
Alireza Sharifi
Articles in Press, Accepted Manuscript, Available Online from 11 May 2020
Abstract
High resolution multi-spectral (HRMS) images are essential for most of the practical remote sensing applications. Pansharpening is an effective mechanism to produce HRMS image by integrating the significant structural details of panchromatic (PAN) image and rich spectral features of multi-spectral (MS) ...
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High resolution multi-spectral (HRMS) images are essential for most of the practical remote sensing applications. Pansharpening is an effective mechanism to produce HRMS image by integrating the significant structural details of panchromatic (PAN) image and rich spectral features of multi-spectral (MS) images. The traditional pansharpening methods incur disadvantages like spectral distortion, spatial artifacts and lack of details preservation in the fused image. The pansharpening approach proposed in this paper is based on integrating wavelet decomposition and convolutional sparse representation (CSR). The wavelet decomposition is performed on PAN and MS images to obtain low-frequency and high-frequency bands. The low-frequency bands are fused by exploring the CSR based activity level measurement while the high-frequency bands are fused based on the constituent wavelet energy. Finally, the HRMS image is restored by implementing the inverse transform on fused bands. The fusion rules are constructed, thus to transfer the crucial details from source images to the fused image effectively. The proposed method produces HRMS images with rational spatial and spectral qualities at relatively less computational effort compared with most of the traditional sparse representation methods. The visual outcomes and quantitative measures approve the eminence of the proposed fusion framework.
